By Wednesday morning, his struggling operation decided to shoot for two-out-of-three.

In the latest sign the former House speaker’s White House bid is on the ropes, it has canceled all travel to Kansas before Saturday’s GOP caucuses there and its spokesman, R.C. Hammond, said Alabama and Mississippi, which vote March 13, are must-wins if Mr. Gingrich is to remain credible.

Consider this exchange between Washington Wire and Mr. Hammond.

Q: Newt said he had to win Georgia to remain a credible candidate. Does he have to win Alabama and Mississippi to remain a credible candidate?

A: Yes.

Q: He has to win?

A: Yes.

Mr. Hammond would not say if Mr. Gingrich would drop out if he loses either of those states.

Mr. Gingrich has long staked his campaign on a so-called southern strategy. While the former House speaker won his home state of Georgia on Tuesday, that path has been complicated by Rick Santorum, whose conservative stance on social issues helped him win Tennessee and Oklahoma.

Mr. Santorum is also running ads here in Alabama. In response, the Gingrich campaign purchased air time Tuesday on Fox News in Alabama and Mississippi, though the size of the buy remained unclear. It plans to run an energy-focused spot that, among other things, features a man being held hostage by a gas pump. It has also cut negative ads targeting Mr. Santorum but has made no plans yet to air them.

Mr. Gingrich was set to take the stage here Wednesday in front of a black backdrop and a large sign touting his proposal for $2.50 a gallon gasoline. About 10 minutes before he took the stage, both the backdrop and the sign topped over.